Darkwhisper Gorge was an area in the far south of Winterspring which consisted of a network of tunnels and chasms. This area was inhabited by elitedemons of an approximate five-man difficulty, although easily solable by a level 80.

Darkwhisper Gorge

This treacherous cavern laid along Winterspring Valley's southern slope. Poisonous green vapours bubbled out of acid pools deep within the bottom of the gorge. Malevolent sounds echoed from a cave at the furthest end of the gorge, leading some night elves to believe that demons may have taken refuge in the toxic depths.WRPG 213

The demons in this area were important to a number of quests, unlike their Blasted Lands counterparts.

"Unused Instance Portal" - An instance portal with a runed gate existed in the lower part of the Gorge. It could be found

A screen shot of the unused instance portal. If one looks closely, they can see trees.

at [50, 83]. This was most likely the entrance to Hyjal, as one could see trees and grass behind the portal, especially when using Far Sight: the trees and vegetation matched the ones from the Caverns of Time Mount Hyjal raid instance, and a giant, blackened crater at the end of a winding path trough the area could indeed be the effect of Archimonde's destruction.